1. Field of the Invention
The present invention relates to a wafer holding body for use in a wafer prober for testing a semiconductor wafer, a heater unit including the wafer holding body and a wafer prober.
2. Description of the Background Art
Conventionally, in a step of testing a semiconductor wafer, a heating process is performed on a semiconductor wafer as a process target. Here, a burn-in step is performed in which a semiconductor wafer is heated to a temperature higher than a normally used temperature to accelerate a defect in a semiconductor chip that is potentially defective for removal in order to prevent a defective after shipment.
In this burn-in step, before a semiconductor wafer having a circuit formed therein is cut into individual semiconductor chips, the electric characteristics of each semiconductor chip are determined while the semiconductor wafer is heated, thereby removing a defective. In this burn-in step, reduction of the process time is strongly requested in order to improve a throughput.
In such a burn-in step, a heater unit for heating a semiconductor wafer is used which includes a wafer holding body for holding a semiconductor wafer. The wafer holding body used in a conventional heater unit uses a flat plate-like metal plate so that the entire back surface of a semiconductor wafer should be brought into contact with a ground electrode.
In the burn-in step, a semiconductor wafer having a circuit formed therein is placed on a wafer-placing surface of the wafer holding body which is a metal plate in order to determine the electric characteristics of a semiconductor wafer. In determining the electric characteristics of a semiconductor chip, a determiner called a probe card including a number of probe pins for supplying power is pressed against a semiconductor wafer at a force of a few tens of kgf to a few hundreds of kgf.